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DETERMINATION OF C2-C5 HYDROCARBONS IN THE ATMOSPHERE AT LOW PARTS PER 109 TO HIGH PARTS PER 1012 LEVELS

DETERMINATION OF C2-C5 HYDROCARBONS IN THE ATMOSPHERE AT LOW PARTS PER 109 TO HIGH PARTS PER 1012 LEVELS

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Title: DETERMINATION OF C2-C5 HYDROCARBONS IN THE ATMOSPHERE AT LOW PARTS PER 109 TO HIGH PARTS PER 1012 LEVELS
Author: Khedim, A
Ehhalt, D.H
Rudolph, J.
Jebsen, C
Abstract: By far the most abundant hydrocarbon in unpolluted air is methane (mixing
ratio cu. 1.6 ppm). The mixing ratios of other hydrocarbons are typically in the low
parts per lo9 (ppb) and parts per 10” (ppt) ranges. Although methane is several
orders of magnitude more abundant in clean air, it is conceivable that other hydrocarbons
are still of considerable importance to clean air photochemistry, because
their reaction with hydroxyl radicals proceeds much faster than that of methane.
Owing to this high reactivity of many of the light non-methane hydrocarbons
(NMHC), mixing ratios of NMHC as low as a few ppb or several ppt can have a
considerable influence on the photochemistry of unpolluted air. For this reason a gas
chromatographic method has been developed that permits the determination of several
C2-C, hydrocarbons with detection limits of a few ppt from grab samples of
0.5-Z dm3 (STP).
The samples are collected in evacuated 2-1 stainless-steel containers with metal
bellows-sealed stainless-steel valves. These sample collection and storage cans are
specially pre-treated and cleaned to avoid changes in sample composition during
transport of the samples to the laboratory. In the laboratory the samples are analysed
by enrichment of the hydrocarbons on a packed pre-column at sub-ambient temperatures
(L’LI. - 35°C) and subsequent separation on a 7 m x 0.8 mm I.D. packed column
(Spherosil XOB 075). A flame-ionization detector is used. This method allowed survey
measurements on a global scale of C,-C, hydrocarbons. which gave an estimate of
the contributions of light hydrocarbons to atmospheric photochemical reactions.
Type: Article
Rights: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TG8-44BF161-C5&_user=866177&_coverDate=11%2F06%2F1981&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1193813513&_rerunOrigin=google&_acct=C000045519&_version=1&_urlVersion=0&_userid=866177&md5=a958f2d8acf25513dc106239152ea001
http://www.sciencedirect.com/science/journal/00219673
URI: http://hdl.handle.net/10315/2933
Citation: J. Chromatogr., 217, 301-310
Date: 1981

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